Coronavirus vaccine (illustrative)
Coronavirus vaccine (illustrative) Yonatan Sindel/Flash90

Sheba Medical Center, Israel’s largest medical center and a Newsweek top-10 ranked world’s best hospital for the last four years, published a study Thursday in the New England Journal of Medicine demonstrating the necessity for mRNA COVID-19 vaccine booster doses, and pinpointing the ideal timing for administering them.

The research, led by Dr. Michal Canetti at Columbia University, New York, and Professor Gili Regev-Yochay, studied the effectiveness of the BNT162b2 vaccine (Pfizer–BioNTech) in Sheba Medical Center healthcare workers, and concluded that the protection achieved by a third or fourth vaccine dose was significantly stronger than that of two doses alone.

The study measured both immune response and the effectiveness of the vaccine in preventing omicron infection. Results displayed that the protection achieved by a third or fourth vaccine dose is much higher than two doses alone. Further observations concluded that the third and fourth doses induced a similar immune response, peaking within a month of being administered and waning gradually over about four months. The study also determined that the overall vaccine effectiveness in preventing omicron infection was 40% during the first six months, with rates reaching as high as 50% during the initial months.

The peer-reviewed study was conducted on a cohort of healthcare workers at Sheba Medical Center, who had not previously contracted the coronavirus. Researchers tested the immune response of ~6,000 participants by measuring antibody levels monthly, and comparing them after the second, third, and fourth vaccinations.

The study concluded that the correlation between antibody levels and risk of infection, as well as the waning immunogenic response within four months of receiving an mRNA COVID-19 vaccine, demonstrates the need to administer boosters seasonally, like the influenza vaccine, or to be timed to coincide with disease waves.

“Our latest research sheds further light on the direct relationship between antibodies and protection against coronavirus infection, including omicron,” said Professor Gili Regev-Yochay, Director of the Infectious Diseases Unit at Sheba Medical Center. “With protection clearly waning after four months, individuals and health systems must plan their booster timing wisely, taking into consideration not only surges in infection but also personal medical conditions, upcoming events and travel, and higher-risk seasons.”